Cardinal Infrastructure Group Inc. Stock Compensation Disclosure

12. Stock-Based Compensation

2025 Stock Incentive Plan

Cardinal Infrastructure Group Inc. adopted the 2025 Stock Incentive Plan (the “2025 Plan”) on November 13, 2025, with stockholder approval on the same date. The 2025 Plan is designed to attract, retain, and motivate employees, officers, directors, and consultants by providing for equity‑based compensation aligned with long‑term stockholder value. It authorizes up to 3,660,656 shares of Class A common stock for issuance, with the share reserve eligible for an automatic annual increase of up to 5% of outstanding shares beginning with the first fiscal year after the Company’s registration date, unless the Compensation Committee elects otherwise. Shares underlying awards that are forfeited, canceled, expired, or settled in cash are returned to the plan.

The 2025 Plan may be used to grant stock options (both incentive and nonqualified), restricted stock, restricted stock units, stock appreciation rights, and other stock‑based awards. It is administered by the Board of Directors or a designated committee, which has broad authority to determine award terms, vesting conditions, performance goals, and to interpret the plan, including the ability to accelerate vesting in certain circumstances. The 2025 Plan includes a detailed definition of a Change in Control, covering specified acquisitions of voting power, board turnover, mergers, consolidations, and significant asset transactions. The plan will remain in effect until November 13, 2035, unless earlier terminated or extended.

As of December 31, 2025, the December 2025 Director Stock Awards discussed below were issued under the Plan.

October 2025 Employee Unit Awards

On October 1, 2025, the Company granted 113 fully vested LLC units in Cardinal Civil Contracting Holdings LLC to employees as compensation for services. These units were structured as profits interests at issuance. In connection with the Company’s reorganization and initial public offering ("IPO") in December 2025, all outstanding LLC units were converted into 274,547 shares of the Company’s common stock pursuant to the applicable conversion ratio.

The grant‑date fair value of the awards was $5,765,487, which was fully recognized as stock‑based compensation expense in October 2025 because the awards were immediately vested. The fair value per unit at the October 1, 2025 grant date was estimated at $21.00 per unit (equivalent to $21.00 per share of common stock on an as-converted basis), based on the anticipated initial public offering price derived from the Company's ongoing discussions with its underwriters, which was equal to the actual initial public offering priced. Management concluded that the anticipated initial public offering price, which was determined based on observable market inputs including comparable company valuations and institutional investor indications, represented the best available evidence of the fair value of the Company's common equity as of the grant date. No discount for lack of marketability or other adjustments were applied given the proximity of the grant date to the IPO (approximately two months) and the absence of material changes in the Company's business or financial condition during the intervening period. The fair value measurement is classified within Level 2 of the fair value hierarchy as the significant inputs to the valuation were derived from observable market data, although a quoted market price for the Company's shares was not yet available as of the grant date.

December 2025 Director Stock Awards

In November 2025, the Board of Directors approved a Non-Employee Director Compensation Program under which directors receive annual cash retainers and equity grants pursuant to the 2025 Stock Incentive Plan. Each non-employee director is entitled to an annual cash retainer of $75,000 and an annual grant of restricted stock units (RSUs) with a grant date fair value of $100,000, generally awarded at the Company’s annual meeting and vesting on the earlier of the next annual meeting or the first anniversary of the grant date. Committee chairpersons receive an additional annual RSU grant valued at $12,500, and other committee members receive RSUs valued at $5,000 annually. Directors may elect to receive their cash retainer in the form of RSUs, which vest quarterly. In connection with the Company’s IPO, newly appointed directors received RSU grants with a fair

value of $18,750 (in lieu of a prorated cash retainer for 2025), vesting on December 31, 2025, as well as RSUs valued at $100,000 plus applicable committee grants, each vesting on the first anniversary of the grant date.

As a result of these grants, the Company issued 25,829 RSU’s in December 2025 and recognized $103,105 of stock-based compensation expense in December 2025. The fair value of the restricted stock units was based on the Company’s IPO price of $21.00 per share, which represents a Level 1 input under the fair value hierarchy, as the awards were granted on the IPO date. Of the RSU's issued, 3,568 vested immediately and had a total grant date fair value of $74,928.

As of December 31, 2025, the Company had $439,304 of unrecognized compensation cost related to 22,261 unvested awards, based on a weighted‑average grant‑date fair value of $21.00 per award. This amount is expected to be recognized over a weighted‑average period of 12 months, corresponding to the remaining service period through December 31, 2026.